i still run a pIII-500 with 640 mb of ram and a 17 gb hd (it was sold with windows 98 on it, in 1999) as a multimedia pc in my living room. all this thing has to do is
1) connect to an external drive with mp3s and send that signal out to a stereo.
2) connect to youtube so i can watch something as i eat.
it's running a stripped down n-lite version of xp with all the services off. the boot-up is slow, but if i was just to pop around the desktop like you are here it would be every bit as fast as that. anything beyond 500 mhz is far from a crappy machine. windows has historically just been awful with memory management.
a linux install on my or your machine would take better advantage of the hardware and i have little doubt that 8 would be just as snappy on my 500, if it would install without giving me an error. it can run word fine. it can play local videos without a hassle. etc. really, just about anything you'd need it for...
...except browsing with more than one tab, but that has more to do with bad design from browsers and web page admins that just throw memory out the window and expect people to run silly specs to compensate for it...
